1. Technical Field
This invention generally relates to trailers, and more specifically relates to a dolly for towing trailers.
2. Background Art
With vehicles, such as motorhomes for example, it is often desirable to tow trailers, such as motorsport trailers for example. However, problems arise from towing trailers with motorhomes. For example, in some situations, such as when a motorsport trailer approaches its gross trailer weight (the weight of the trailer fully loaded in its actual towing condition), the trailer tongue weight (the downward force exerted on the ball mount by the trailer coupler) can approach a weight of up to 2000 lbs or more. Tongue weights of this magnitude dangerously overload the weight capacity of the motorhome""s rear end when traveling. That is, the amplified load to the motorhome frame that occurs during the bounces and rebounds over bumps, holes, bridges, and the like during travel can damage the frame, chassis, and/or body of the motorhome.
Additional problems arise when the trailer is towed in a position that is not horizontal with respect to the road. This produces further dangerous forces that a towing vehicle is not designed to support. Furthermore, as is common in conventional trailers, the tire-wheel assemblies are in a fixed position. This creates difficulty is turning the towing vehicle with the trailer attached, and in backing up a trailer, such as backing a motor boat down a boat ramp into a lake for example
Accordingly, what is needed is a dolly for towing trailers that overcomes the frame, chassis, and/or body damage to towing vehicles, the horizontal alignment of the trailer, and the steering drawbacks of conventional modes of towing a trailer.
The present invention provides dolly embodiments for towing trailers that overcome the aforementioned drawbacks associated with towing trailers without changing or modifying a trailer and/or trailer tongue. Dolly embodiments of the invention are separate, independent towing systems used between trailers and towing vehicles. As such, they carry the weight of trailers, thereby relieving the stress on the towing vehicle. Moreover, dolly embodiments of the invention have self-steering ability. Generally, a dolly embodiment of the invention for towing trailers may comprise a main framework, a tongue assembly, stabilizing shocks, an axle, an axle platform, a steering assembly, and/or tire-wheel assemblies.
The main framework may be rectilinear in shape and may be comprised of two side members (e.g. rectilinear tubes) with aligning holes through the front ends thereof for pivotally coupling with the tongue assembly. The side members may be coupled together by a front lateral member (e.g. rectilinear tube), a steering bracket, and a rear end plate. The steering bracket may include a steering hub surrounded by a 5 bolt, 4{fraction (1/2)}xe2x80x3 bolt circle, and may be used to retain a spare tire-wheel assembly atop the main framework. Additionally, the main framework may also comprise a ball mount adjusting member used in conjunction with an adjustable ball mount assembly.
The hinged tongue assembly may comprise a lateral member (e.g. rectilinear tube) with a pair of framework mounting brackets at each end thereof. The pairs of mounting brackets may have aligning holes there through and, along with the lateral holes in the front ends of the side members, may be configured to receive a fastener to pivotally couple the tongue assembly to the main framework. An adjusting bracket configured to provide hitch shank height a adjustment for level towing may be coupled the front central portion of the lateral arm and may have a plurality of aligning holes there through for adjustably coupling with a hitch shank assembly. The adjustable hitch shank may be L-shaped, with one portion configured to slidably, removably insert into the hitch receiver of a towing vehicle. The other portion of the hitch shank may have a pair of aligning holes there through and, along with the aligning holes in the adjusting bracket, may be configured to receive a fastener to adjustably couple the hitch shank assembly to the adjusting bracket.
A pair of stabilizing shocks may be located underneath the main framework with their front ends coupled adjacent one another to the tongue assembly and their rear ends splayed apart and coupled to opposing brackets of the axel platform.
The axle may be a torsion axel that uses the flexibility of steel torsion bars or tubes, twisting lengthwise to provide spring action. Instead of the flexing action of a leaf spring, or the compressing-and-extending action of a coil spring, the torsion bars twist to exert resistance against up-and-down movement. Accordingly, the torsion axle may comprise two control arms of spring steel. One end of each torsion bar may be fixed solidly to one end of a spindle; the other end may be coupled to inner end of one of the lower cross arms and may pivot through a bushing. As the lower control arms rise and fall with wheel movement, the torsion bars twist and absorb more of the road shocks before they can reach the main framework of the dolly. The torsion bars untwist when the pressure is released, just like a spring rebounding after being compressed.
The axle platform may comprise a platform (e.g. rectilinear tube) and a pair of opposing brackets. The pair of opposing brackets may be coupled to rear end 1 portions of the stabilizing shocks, and the torsion axle may be fixed to a bottom side of the axle platform.
A steering assembly may comprise a spindle and a steering hub. The steering hub may be coupled to the steering bracket of the ma in framework and may be configured to retain a spare tire-wheel assembly top the main framework. The spindle may be rotatably coupled to the steering hub and may be fixedly coupled to a center portion of a top side of the axle platform. As a towing vehicle turns, the steering assembly allows the torsion axle to rotate and provide self-steering capabilities to enable greater control over the trailer being towed.
Each tire-wheel assembly may be coupled to one of the spindles fixed to one of the control arms of the torsion axle. This may be accomplished by the use of a hub coupled to the spindle, the hub also being configured to retain a tire-wheel assembly in a functional position. Bearing Buddies(copyright), which keep water and dirt out of hubs and bearings may be located on outer ends of the hubs. The tires may also be high-speed tires with a 580xc3x978 tire size.
The foregoing and other features and advantages of the invention will be apparent to those of ordinary skill in the art from the following more particular description of the invention and the accompanying drawings.